1. Field of the Invention
The present invention relates to ophthalmic compositions and methods useful to treat dry eye, or to diagnose, cure, mitigate, treat, or prevent dry eye syndrome in man or other animals.
2. Background of the Art
Dry eye is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tears film instability with potential damage to the ocular surface. The normal tear film is a relatively stable, thin film composed of a superficial lipid layer and an aqueous layer intermixed with a mucus gel layer which is partially adherent to the corneal and conjunctival surface epithelium. Natural tear film is important for the lubrication and maintenance of the refractive surface of the eye. Dry eye syndrome is a complex disease characterized by a dysfunction of one or more components of the tear film, leading to the loss of tear film stability, a hyperosmotic shift in the tear film osmotic balance, and/or an inadequate amount of fluid on the ocular surface. This is characterized by rapid break-up of the tear film and numerous symptoms, including burning/stinging, foreign body sensation, itching, and photophobia. The majority of patients with dry eye syndrome are prescribed or recommended artificial tears. Also recommended are lid compresses and scrubs, and addition of essential fatty acids to the diet.
Dry Eye Syndrome is a common disorder of the normal tear film that results from one of the following: decreased tear production, excessive tear evaporation, an abnormality in the production of mucus or lipids normally found in the tear layer.
Aqueous (watery) tear deficiency is caused by either poor production of watery tears or excessive evaporation of the watery tear layer.
Poor production of tears by the tear glands may be a result of age, hormonal changes, or various autoimmune diseases, such as primary Sjogren syndrome, rheumatoid arthritis, or lupus.
Evaporative loss of the watery tear layer is usually a result of an insufficient overlying lipid layer. Some medications, such as antihistamines, antidepressants, beta-blockers, and oral contraceptives, may decrease tear production. If blinking is decreased or if the eyelids cannot be closed, the eyes may dry out because of tear evaporation.
Reading, watching TV, or performing a task that requires close attention with the eyes, may decrease the blinking, allowing excessive evaporation of the tears.
LASIK and other vision correction procedures can cause dry eyes after they penetrate the eye's surface and reduce corneal nerve sensitivity. Afterwards the eye fails to sense the need for lubrication and inadequate tear production results. New ophthalmic compositions for treating eyes and methods of treating dry eyes have been discovered.